1. Field of the Invention
The present invention is generally concerned with torsional damper devices comprising at least two coaxial parts disposed to rotate relative to one another within defined limits of relative angular movement against elastic means hereinafter referred to as circumferentially acting elastic means.
2. Description of the Prior Art
This type of torsional damper is normally incorporated in the design of a friction clutch, particularly for automotive vehicles, in which case one coaxial part carries a friction disk designed to roatate with a first shaft, in practice a driving shaft and the motor output shaft in the case of an automotive vehicle, whereas another of said coaxial parts is carried on a hub designed to rotate with a second shaft, in practice a driven shaft, and the gearbox input shaft in the case of an automotive vehicle.
This type of torsional damper is used to permit regulated transmission of rotational torque applied to one of its coaxial parts where another is itself subject to a rotational torque. It is thereby able to filter vibrations which may arise at any point in the kinematic system in which it is incorporated, extending from the motor to the driven road wheels in the case of an automotive vehicle.
In practice, friction means are deployed between the coaxial parts of the damper device concerned to provide the necessary damping.
More often than not, such friction means comprise friction rings disposed axially between said coaxial parts.
The present invention is particularly directed towards the case where one, and in practice all, of the coaxial parts of the torsional damper device concerned comprises at least one transversely disposed annular flange, commonly referred to as a hub flange, or guide ring in which are formed holes adapted to house elastic members which form part of the associated circumferentially acting elastic means.
More often than not, the elastic members bear directly in the circumferential direction on the corresponding radial edge of the holes in which they are disposed, these holes in at least some of said flanges having more or less extensive members along at least one of their circumferential edges adapted to retain elastic members of this kind.
It has already been proposed, in particular in French Pat. No. 740 783, in which one of the coaxial parts of the torsional damper device concerned comprises a hub flange and the other comprises two guide rings disposed one on each side of said hub flange and the guide rings utilized have no member for retaining the elastic means, to dispose in the circumferential direction between each of the elastic members and the edges of the holes in the guide rings in which the elastic member is disposed a member constituting a chock, hereinafter referred to for convenience as a bearing member, adapted to retain the elastic member.
A general object of the present invention is to draw additional benefit from a bearing member of this kind, whether utilized to retain the corresponding elastic member or for any other purpose.